Seal

ABSTRACT

The invention provides a seal for sealing between two members ( 1, 3 ) which are mutually movable so as to slide relative to each other. One of the members comprises a body ( 3 ) with a channel ( 2 ) formed therein. The channel ( 2 ) has a longitudinal axis and the other member ( 1 ) is receivable in the channel ( 2 ) so that the two members ( 1, 3 ) slide relative to each other in a direction parallel to the longitudinal axis. The first member ( 1 ) has at least one deformable plastics rib ( 4, 5, 6, 7, 8, 30, 34 ) formed on a surface thereof. The rib ( 4, 5, 6, 7, 8, 30, 34 ) faces the second member ( 3 ) and in use deforms on abutment with the wall of the channel ( 2 ) of the second member ( 3 ) to provide a seal between the two members ( 1, 3 ) when they are stationary or moving relative to one another. An endless plastics skirt ( 22 ) may be provided around the external surface of the first member ( 1 ) with the rib ( 4, 5, 6, 7, 8, 30, 34 ) being formed around the external surface of the skirt ( 22 ). The skirt ( 22 ) is deformable to adjust to irregularities in the shape of the channel ( 2 ) to allow the rib to seal between the skirt ( 22 ) and the wall of channel ( 2 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 11/658,799, filed Jul. 29, 2007; which is theNational Stage of International Application No. PCT/US2005/027288, filedJul. 29, 2005; which claims the benefit of U.S. Provisional ApplicationNo. 60/592,698, filed Jul. 30, 2004; the contents of which areincorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to a seal and in particular to a sealuseful in systems for the sterile transfer of fluids.

BACKGROUND OF THE INVENTION

Validation and accountability are vital in most scientific industriesand especially so in the pharmaceutical and biotechnological industries.A major challenge to these industries is the need to demonstrateaccurately and reproducibly that sterility is achieved and maintainedthroughout production lines within a plant. This must be done in amanner which meets the stringent requirements of regulatory bodies suchas the United States FDA. Acceptable standards can be difficult to bemet when a substance is transferred from one sterile location to anothersterile location by non direct means. Reliable and durable seal meansmust be employed during such transfer.

SUMMARY OF THE INVENTION

The present invention provides a seal for sealing between two memberswhich are mutually movable so as to slide relative to each other, afirst one of the members having formed on a surface thereof facing asecond of the members at least one deformable plastics rib forcontacting the second member and sealing between the two members whenthey are stationary or moving relative to one another.

Ideally, the first one of the two members is constructed of plasticsmaterial and the rib may be formed integrally therewith.

The rib is sufficiently deformable and flexible so that it drags orwipes along the surface of the second member with which it is in contactas the two members slide with respect to one another. A plurality ofsealing ribs may be provided, axially spaced apart from one anotheralong the path of relative movement between the members.

In a most preferred embodiment, one of the members comprises a body witha first channel formed therein, the channel having a longitudinal axisand the other member being receivable in the channel so that the twomembers slide relative to each other in a direction parallel to thelongitudinal axis, a first one of the members having formed on a surfacethereof facing a second of the members the at least one deformableplastics rib.

The rib itself may have different shapes and configurations, any ofwhich will be suitable provided that they are such as to provide aneffective seal between the members. For example, the rib may be formedwith its free, sealing edge shaped as a U, V, W, “truncated V”,“truncated W” or any other suitable cross-sectional shape.

Of particular benefit is the use of such a sealing arrangement in avalve where a piston slides within a housing so as to open or close anopen end of the valve. In such a case, it is advantageous to form therib about the radially outwardly facing surface of the piston with therib extending radially outwardly therefrom to impinge upon the interiorsurface of the housing.

Furthermore, it is of particular benefit to provide at least two ribsaccording to the invention on the surface of the first member so thatthe distance between the ribs along the path of travel of the twomembers relative one another is greater than a predetermined distance oftravel of the two members relative one another along the path. Such anarrangement allows one of the ribs to always remain within apredetermined area on the surface of the second member. Such an area mayfor example be a sterile area inside a valve for sterile transfer offluids in which a piston travels along a housing in order to open orclose the valve. The above described arrangement of the ribs allows oneof the ribs to always remain within the sterile area so as to maintainsterility inside the valve. The above described arrangement of the ribsmay be used with various valves for sterile transfer of fluid, such asfor example, the valves described in WO 03/090842 and WO 05/012775.

The seal of the present invention may use as an alternative or additiona known sealing means, such as an O-ring seal.

Tolerances for transverse dimensions of the channel in the body, for thereceivable member and for the at least one deformable plastics rib maybe rather strict in order to enable the rib to seal between the twomembers. These tolerances therefore may be difficult or costly to meet.In view of this, it is advantageous to provide an adaptor between thewall of the channel and the receivable member, the adaptor comprising anendless skirt provided around a surface of one of the channel or thereceivable member facing the other member, the skirt being connected tothe member and being movable with the member so that mutually facingsurfaces of the skirt and of the member to which the skirt is attachedare spaced to define a gap therebetween, the at least one deformableplastics rib being formed around one of the mutually facing surfaces ofthe skirt and said other member, the skirt being sufficiently deformableand flexible in order to enable adjustment of the skirt to accommodatedimensional irregularities between the skirt and said other member whenthe two members are engaged so as to allow the at least one rib to sealbetween the mutually facing surfaces of the skirt and said other memberwhen the two members are stationary or moving relative each other. Theprovision of such a deformable skirt permits less strict tolerances tobe applied in the manufacture of the two members.

Preferably, the skirt comprises a free end portion and a base portionabout which the skirt is connected to the member.

In a most preferred arrangement, the skirt is formed around thereceivable member and the rib is formed around the external surface ofthe skirt so that in use the skirt deforms in the channel to adjust todimensional irregularities between the external surface of the skirt andthe wall of the channel to enable the rib to seal therebetween.

Ideally, the skirt is sufficiently resilient to regain its originalstate upon withdrawal of deformation.

Of particular benefit is the provision of the skirt about the outwardlyfacing surface of the piston in the above described valve with the ribbeing formed around the external surface of the skirt.

In a most preferred arrangement, the skirt is provided as an attachmentconnectable to the member via a coupling means. Preferably, the couplingmeans comprises a snap-fit arrangement between the skirt and the othermember. Ideally, the snap-fit arrangement a series of alternatingresiliently deformable ribs and grooves formed around each of themutually facing surfaces of the skirt and the other member, the ribs ofthe skirt and the other member being deformable on assembly so as toengage with the corresponding grooves of the member and the skirt. Inthe arrangement where the skirt is provided as an attachment couplablewith the receivable member, the skirt is provided open ended.

In one arrangement, the skirt may be formed integrally with the member,preferably, by forming an endless slot in the material of the member sothat the slot is defined by mutually facing endless surfaces of theskirt and the member.

The preferred material for the manufacture of the skirt is plastics, butother suitable resiliently deformable materials may be used.

Ideally, the skirt is configured to be sufficiently resilientlydeformable under a predetermined pressure range of fluid supplied into agap between the mutually facing surfaces of the skirt and the member towhich the skirt is attached, so as to deflect towards the other memberthus enhancing the sealing action of the at least one rib between theskirt and the other member. This feature of the skirt is particularlyuseful in an application in a valve for sterile transfer of fluids.Typically, in such valves, fluid being transferred through the valve issupplied under a higher line pressure. It is advantageous therefore tolocate the skirt on the piston of the valve with the opening of the gapfacing against the direction of the fluid flow so that the part of thefluid that enters the valve also flows into the gap.

In one arrangement, instead of forming a plurality of ribs around theskirt or the other member it is possible to form a thickening on alength of the skirt or the other member parallel the longitudinal axisof the channel which would otherwise be occupied by a pair or more ofspaced apart ribs.

It will be appreciated that the above described adaptor is not limitedto the use only with the above described sealing ribs. Therefore, inanother aspect, the invention provides an adaptor for connecting twomembers, one of the members comprising a body with a channel formedtherein, the channel having a longitudinal axis and the other memberbeing receivable in the channel so that the two members can sliderelative to each other in a direction parallel to the longitudinal axis,the adaptor comprising an endless skirt provided around a surface of oneof the channel or the receivable member facing the other member, theskirt being connected to the member and being movable with the member;wherein mutually facing surfaces of the skirt and the member to whichthe skirt is attached are spaced to define a gap therebetween; the skirtbeing sufficiently deformable and flexible in order to enable adjustmentof the skirt to accommodate dimensional irregularities between the skirtand said other member when the two members are engaged thus permittingless strict tolerances to be applied in the manufacture of the twomembers. The adaptor may advantageously be provided with one or moresealing ribs as herein described.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the accompanyingdrawings which show, by way of example only, several embodiments of theseal according to the invention

In the drawings:—

FIG. 1 is a side elevation of a first embodiment of a sealing rib formedin a cylindrical body;

FIG. 2 is an enlarged portion of FIG. 1 showing the sealing rib;

FIG. 3 is a side elevation of a second embodiment of a sealing ribformed in a cylindrical body;

FIG. 4 is an enlarged portion of FIG. 3 showing the sealing rib;

FIG. 5 is a side elevation of a third embodiment of a sealing rib formedin a cylindrical body;

FIG. 6 is an enlarged portion of FIG. 5 showing the sealing rib;

FIG. 7 is a side elevation of a fourth embodiment of a sealing ribformed in a cylindrical body;

FIG. 8 is an enlarged portion of FIG. 7 showing the sealing rib;

FIG. 9 is a side elevation of a fifth embodiment of a sealing rib formedin a cylindrical body;

FIG. 10 is an enlarged portion of FIG. 9 showing the sealing rib;

FIG. 11 is a perspective view of a sliding member having one sealing ribof the first embodiment;

FIG. 12 is an elevation of a portion of a piston having three sealingribs of the fourth embodiment;

FIG. 13 is an enlarged sectional view of a portion of FIG. 12 showingthe sealing ribs;

FIG. 14 is a sectional elevation of the fourth embodiment of the sealingrib used in combination with an O-ring seal;

FIG. 15 is a cross-sectional elevation of a cylinder having an adaptorin a form of a resiliently deformable skirt provided at each end of thecylinder, the skirt having sealing ribs according to the inventionformed on the external surface of the skirt;

FIG. 16 is an enlarged view of area X of FIG. 15 showing in detail theskirt and the sealing ribs both according to the invention;

FIG. 17 is an enlarged view of area Y of FIG. 16 showing in detail oneof the sealing ribs provided on the skirt;

FIG. 18 is a cross-sectional elevation of a piston having a pair ofskirts similar to those shown in FIG. 15, the piston being adapted totravel within a housing without projecting outwardly from the housing;

FIG. 19 is an enlarged view of area W of FIG. 18 showing the skirt withthe sealing ribs at one end of the piston;

FIG. 20 is an elevation of a portion of the piston of FIG. 18 showingthe exterior of the skirt at the opposite end of the piston;

FIG. 21 is a cross-sectional elevation of a piston having a pair ofskirts similar to those shown in FIGS. 15 and 18, the piston having abarbed fitting for connecting the piston to another device;

FIG. 22 is an enlarged view of area Z of FIG. 21 showing the skirt withthe sealing ribs proximal the end of the piston having the barbedfitting;

FIG. 23 is a cross-sectional elevation of a cylinder having a skirtsimilar to that shown in FIG. 15 but provided as an attachment to thecylinder;

FIG. 23 a is an enlarged view of area S of FIG. 23;

FIG. 24 is an elevation of a portion of a piston having a skirt similarto that shown in FIG. 15 but provided as an attachment to the piston;

FIG. 25 is an enlarged partial elevation of the skirt of FIG. 23;

FIG. 25 a is an enlarged view of area P of FIG. 24 showing a snap-lockarrangement of the skirt;

FIG. 26 is an enlarged view of area Q of FIG. 24 showing a sealing ribin accordance with the invention formed around the exterior of theskirt;

FIG. 27 is an elevation of a portion of a piston similar to that shownin FIG. 23 but without a skirt;

FIG. 28 is an enlarged view of area V of FIG. 27;

FIG. 29 is a schematic cross-sectional elevation of a piston and ahousing exaggeratedly showing tapered surfaces of the exterior of thepiston and the wall of channel in a housing in which the piston travels;and

FIG. 30 is an enlarged schematic cross-sectional view of a piston ofFIG. 23 positioned within a housing showing a straight area in thehousing for contact with the ribs on the skirt.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIGS. 1 to 10 there is shown a cylinder 1 slidablyreceivable in a circular channel 2 of a body 3. A seal member accordingto the invention is provided in a form of deformable ribs 4, 5, 6, 7, 8of FIGS. 2, 4, 6, 8, and 10 respectively formed around the externalsurface of the cylinder 1. The rib 4 has a U-shape in cross section, theribs 5, 7 and 8 are V-shaped in cross-section and the rib 6 is W-shapedin cross-section. The diameter of the cylinder 1 is smaller than thediameter of the channel 2 whereas the most peripheral region 9 of thesurface of the rib 4, 5, 6, 7, 8 projects beyond the external surface 1a of the cylinder 1 so that the diameter of the most peripheral region 9is greater than the diameter of the channel 2. The cylinder 1 is made ofa plastics material and the rib 4, 5, 6, 7, 8 is formed integrally withthe cylinder. Other means of forming the rib on the cylinder are alsopossible, some of which will be discussed below with reference to FIGS.15 to 26.

In use, when the cylinder 1 is loaded into the channel 2, the mostperipheral region 9 of the surface of the rib 4, 5, 6, 7, 8 abuts thewall of the channel 2 and deforms in order to permit the cylinder 1 toenter the channel 2. The abutment is sufficiently close and tight that aseal is formed between the wall 10 and the rib 4, 5, 6, 7, 8. This sealremains intact during subsequent movements of the cylinder 1 along thechannel as the deformable rib 4, 5, 6, 7, 8 drags or “wipes” along thewall of the channel 2.

FIG. 11 shows a cylinder 1 in perspective having one rib 5.

FIGS. 12 and 13 show an end portion of a piston 12 for use in a valvefor sterile transfer of fluids. Such a piston is movable within ahousing of the valve in order to open or close an open end of thehousing. The piston 12 has three ribs 7 axially spaced apart from eachother along the path of the piston in the housing. Equally, two ribs 7or a number of ribs in excess of three may be provided, depending on theparticular sealing requirement of a valve.

FIG. 14 shows a rib 7 formed around the external surface of a piston 14disposed in a channel 18 of a housing 15. The rib 7 is used incombination with an O-ring 16 received in a groove 17 of the piston 14to provide a seal between the exterior of the piston 14 and the wall ofthe channel 18.

It will be appreciated, that the seal of the invention is not limited tosealing between members which slide relative to one another about acommon concentric axis. Rather, the seal of the invention can be used toseal between any two surfaces which slide relative to each other. Thesealing rib will be provided substantially perpendicular to the axiswhich is substantially parallel to that in which the surfaces of themembers slide relatively to each other.

Typically the tolerances for the outside diameter of a cylinder 1 andthe inside diameter of a channel 2 of body 3 are rather strict andtherefore are difficult or costly to meet in order to enablesufficiently close and tight abutment of the deformable ribs with thewall of the channel to be achieved. FIGS. 15 to 17 show a cylinder 20having an adaptor in a form of annular endless plastics skirt 22 formedabout each end of the cylinder 20 and encompassing the exterior of anend portion 25 of the cylinder 20. The skirt 22 is sized to bereceivable in the channel 2 of the separate body 3. The skirt 22 has afree end portion 23 and a base portion 24 about which the skirt isconnected to the cylinder 20. A pair of axially spaced apart ribs 30 inaccordance with the invention having a “truncated V” shape is formedaround the external surface of the skirt 22. The skirt 22 issufficiently deformable and flexible so as in use, to enable the skirt22 to accommodate to variations within their tolerances of the diameterof the channel 2 and of the external diameter of the skirt itself oninsertion of the skirt into the channel 2. The provision of the skirt 22ensures sufficiently close and tight abutment of the ribs 30 with thewall of the channel 2 to form a seal between the external surface of theskirt 22 and the wall of the channel 3. For example, a variation fromthe nominal value of the diameter of the channel in the transversecross-section of the channel may result in ovality of the channel inthis cross-section. In the longitudinal cross-section, the variationsmay result in such faults of the profile of the channel as barrelling,saddling, tapering etc. Similar dimensional faults may be present in theexternal diameter of the skirt. In FIG. 15, one of the skirts 22 isshown to have an end face 26 flush with an end face 33 of the cylinder20 at one end of the cylinder. It will be appreciated that in othermodifications the free end portion 23 of the skirt 22 may extend beyondan end face of a cylinder.

It is preferred for the skirt 22 to be sufficiently resilientlydeformable to counteract excessive deformation when inserted into thechannel 3 and to regain its original shape upon withdrawal of thedeformation. In effect, in such an arrangement the skirt 22 acts as aresilient adaptor between the channel 3 and the cylinder 20 and permitsless strict tolerances to be applied to the diameter of the channel andthe outside diameter of the skirt 22 thus reducing production costs.

FIGS. 18 to 20 show a piston 31 for use in a valve suitable for steriletransfer of fluids. The piston 31 has a pair of the above describedskirts 22 spaced apart along a longitudinal axis of the piston andencircling the exterior of the piston, each skirt 22 having a pair ofaxially spaced ribs 30. The piston 31 is adapted to travel within ahousing (not shown) without projecting outwardly therefrom. FIGS. 21 and22 show a piston 40 similar to the piston 31 but having a barbed fitting41 at one end for connecting the piston 40 to a separate device. In use,the barbed fitting 41 projects outwardly from the housing. FIGS. 18 and21 show skirts 22 having their free end portions 23 and base portions 24located intermediate the ends of the pistons.

In FIGS. 15 and 16 the skirt 22 is shown formed integrally with thecylinder 20 by forming an annular slot 21 in the material of thecylinder 20 defined by mutually facing inner surface of the skirt 22 andouter surface of the cylinder 20. Similarly, the skirt 22 is formedintegrally with the pistons 31 and 40 in FIGS. 18 to 21. The skirt ofthe invention however is not in any way limited to such an arrangement.In fact, a more preferred option is to provide the skirt as a separateattachment. FIG. 23 shows a cylinder 28 having an open-ended skirt 45 asa separate part fitted around the external surface of the cylinder abouteach end of the cylinder. As shown in FIG. 23 a, each skirt 45 has aninward protrusion 46 at the base portion 24 of the skirt which in use isIn contact with the external surface of the cylinder 28. The provisionof the protrusion 46 allows the annular slot 21 to be defined betweenthe mutually facing inner surface of the skirt and outer surface of thecylinder. FIG. 24 shows an end portion 605 of a piston 60 having an openended skirt 52 as a separate part fitted around the external surface ofthe piston 60. The skirt 52 is coupled with the piston 60 by means of asnap-fit lock 61 (FIG. 24). Although not shown in the drawings, asimilar skirt is provided at the other end of the piston 60. As bestshown in FIGS. 25 and 25 a, the snap-fit lock 61 comprises a pluralityof alternating resiliently deformable ridges 62 and grooves 63 formedaround the inner surface of the skirt 52 facing the piston 60 in use.Matching ridges 68 and grooves 69 (see FIGS. 27 and 28) are formedaround the external surface of the piston 60. Material of the portion ofthe piston 60 comprising the ridges 68 and grooves 69 is selected suchthat the ridges and grooves are resiliently deformable, e.g. plasticsmaterial. On assembly, as the skirt 52 is advanced along the piston 60,the ridges 62 and 68 deform to enable the advancement of the skirt. Whenthe skirt 52 reaches a predetermined position along the piston 60, theridges 62 and 68 are allowed to snap into the grooves 63 and 69,respectively so as to lock the skirt 52 in an engagement with the piston60. Thus the skirt 52 is only permitted to move together with the piston60. It will be appreciated that other means may be provided for couplingthe skirt 52 and the piston 60. The skirt 52 has a pair of axiallyspaced apart ribs 34 according to the invention. As shown in FIG. 26,each rib 34 has a longer tapering side 34 a, a shorter tapering side 34b and a peripheral cylindrical face 34 c intermediate the sides 34 a and34 b.

Although the skirts 22 and 52 are shown having the ribs 30 and 34,respectively, the skirts are equally suitable for any of the ribs 4, 5,6, 7 and 8, or any combination of them, as well as for other shapes inaccordance with the invention.

In an application to valves for sterile transfer of fluids, the skirt22, 52 is adapted to match particular sizes and shapes of the piston andthe housing of a valve. For example, as shown in FIG. 29, a piston 60and a housing 65 of such a valve are typically manufactured by injectionmoulding, and therefore the external surface of the piston 60 and thewall 66 of the channel in the housing 65 taper from one end to the otherin order to facilitate extraction of the piston 60 and the housing 65from their respective moulds. As shown in FIG. 30, in order to allow theribs 34 to seal between the skirt 52 and the housing 65 during thetravel of the piston 60 in the channel, the external surface of skirt 52and a region 67 of the wall 66 of the channel along which the piston 60travels are formed parallel to the path of travel of the piston 60. InFIG. 30, the piston 60 is shown in a position in which the valve isclosed. In order to open the valve, the piston 60 has to travel awayfrom the narrower end of the housing in the direction of arrow G in FIG.30. The length of the region 67 between a first rib 34 proximal thenarrower end of the channel and an end 67 a of the region 67 remote thenarrower end is selected to be at least two times the distance betweenthe ribs 34 to prevent a second rib 34 remote the narrower end of thechannel from travelling beyond the end 67 a of the straight region 67.Some valves can be constructed so that the piston 60 can travel back inthe channel after opening of the valve to re-close the valve. Duringthis travel, the piston 60 moves back beyond its original position shownin FIG. 30 and travels an extra distance towards the narrower end of thechannel in order to re-close the valve. In order to enable thismovement, as shown in FIG. 30, an extra straight length 67 b is providedbetween the first rib 34 and a second end 67 c of the region 67 proximalthe narrower end of the channel 66. In such a valve, the externaldiameters of the two skirts 52 mounted about the ends of the piston 60differ from one another to match the different diameters of the channelat the ends of the housing 65.

As shown in FIG. 24, the piston 60 may have an end face 601 extendingbetween a portion 602 of the piston having a smaller diameter proximalthe end portion 605 of the piston and a portion 603 with a largerdiameter distal the end portion. When the skirt 52 is coupled with thepiston 60, an end face 521 of the skirt 52 facing the end face 601, theexternal surface of the portion 602 and the end face 601 of the pistondefine a groove 80 for receiving a sealing O-ring (not shown), which maybe used in the valve along with the ribs 34.

Another useful feature and function of the skirt 52 in a valve forsterile transfer of fluids will now be described with reference to FIG.24. In use of the valve, the fluid entering the valve at the end portion605 of the piston 60 is usually supplied under an increased pressure. Asthe fluid flows towards the other end of the piston 60, some of thefluid enters the slot 21 and exerts outward pressure on the innersurface of the skirt 52 causing the skirt to deflect outwardly andenhancing the sealing effect of the ribs 34.

The ribs 4, 5, 6, 7, 8, 30, 34 have been described as formed around acylinder 1 but of course such ribs 4, 5, 6, 7, 8, 30, 34 may be providedaround the wall defining the channel 2 of the body 3 in order to form aseal with the external surface 1 a of a cylinder 1 received in thechannel 2. Similarly, the skirt may be formed around the wall in thechannel so that the seal is formed between the inner surface of theskirt and the external surface of the body. Furthermore, the rib or ribsneed not necessarily be formed around the skirt. For example the ribsmay be formed around the channel whereas the skirt with no ribs thereonmay be formed around the body receivable in the channel. Similarly, ribsmay be provided around the body whereas the skirt may be provided aroundthe wall in the channel.

Suitable materials other than plastics materials may be utilised in themanufacture of the skirt.

It will be appreciated that the neither the rib nor the skirt of theinvention is limited to use only in a cylinder or in a circular channeland indeed can be provided around a body or around a wall of a channelof any cross-sectional shape, such as for example square or any othershape suitable to provide a seal.

Furthermore, it will be appreciated that the skirt 22, 52 of theinvention is not limited to the use only in conjunction with the abovedescribed sealing ribs 4, 5, 6, 7, 8, 30, 34. The skirt 22, 52 can beused just for connecting two members without sealing therebetween. Thetwo members can comprise for example a first body with a channel formedtherein, and a second body receivable in the channel so that the twomembers can slide relative to each other. The skirt 22, 52 may beprovided around the wall of the channel in the first body or around theexterior of second body so that on engagement of the two bodies theskirt will resiliently deform to accommodate dimensional irregularitiesbetween the skirt and one of the wall of the channel or the exterior ofthe second body. The provision of the skirt between the two bodies thuspermits less strict tolerances to be applied in the manufacture of thetwo bodies.

It will of course be understood that the invention is not limited to thespecific details as herein described, which are given by way of exampleonly, and that various alterations and modifications may be made withoutdeparting from the scope of the invention as defined in the appendedclaims.

1. A sealing device for sealing between two members which are mutuallymovable so as to slide relative to each other, a first one of themembers having formed on a surface thereof facing a second of themembers at least one deformable plastics rib for contacting the secondmember and sealing between the two members when they are stationary ormoving relative to one another, and in which at least two ribs areformed on the surface of the first member so that the distance betweenthe ribs along the path of travel of the two members relative oneanother is greater than a predetermined distance of travel of the twomembers relative to each other along the path so as to allow one of theribs to always remain within a predetermined area of the surface of thesecond member.
 2. The sealing device as claimed in claim 1, in which thefirst one of the two members is constructed of plastics material and therib is formed integrally therewith.
 3. The sealing device as claimed inclaim 1, in which the rib is sufficiently deformable and flexible sothat it drags or wipes along the surface of the second member with whichit is in contact as the two elements slide with respect to one another.4. (canceled)
 5. The sealing device as claimed in claim 1, in which aplurality of the ribs is provided, the ribs being axially spaced apartfrom one another along the path of relative movement between the parts.6. The sealing device as claimed in claim 1, in which one of the memberscomprises a body with a channel formed therein, the channel having alongitudinal axis and the other member being receivable in the channelso that the two members slide relative to each other in a directionparallel to the longitudinal axis, a first one of the members havingformed on a surface thereof facing a second of the members the at leastone deformable plastics rib.
 7. The sealing device as claimed in claim6, in which an adaptor is provided between the wall of the channel andthe receivable member, the adaptor comprising an endless skirt providedaround a surface of one of the channel or the receivable member facingthe other member, the skirt being connected to the member and beingmovable with the member so that mutually facing surfaces of the skirtand of the member to which the skirt is attached are spaced to define agap therebetween, the at least one deformable plastics rib being formedaround one of the mutually facing surfaces of the skirt and said othermember, the skirt being sufficiently deformable and flexible in order toenable adjustment of the skirt to accommodate dimensional irregularitiesbetween the skirt and said other member when the two members are engagedso as to allow the at least one rib to seal between the mutually facingsurfaces of the skirt and said other member when the two members arestationary or moving relative each other.
 8. The sealing device asclaimed in claim 7, in which the skirt comprises a free end portion anda base portion about which the skirt is connected to the member.
 9. Thesealing device as claimed in claim 7, in which the skirt is formedaround the receivable member and the rib is formed around the externalsurface of the skirt so that in use the skirt deforms in the channel toadjust to dimensional irregularities between the external surface of theskirt and the wall of the channel to enable the rib to sealtherebetween.
 10. The sealing device as claimed in claim 7, in which theskirt is sufficiently resilient to regain its original state uponwithdrawal of deformation.
 11. The sealing device as claimed in claim 7,in which the skirt is provided about an outwardly facing surface of apiston movable within a housing of a valve for sterile transfer offluids with the rib being formed around the external surface of theskirt.
 12. The sealing device as claimed in claim 7, in which the skirtis provided as an attachment connectable to the member via a couplingmeans.
 13. The sealing device as claimed in claim 7, in which thecoupling means comprises a snap-fit arrangement between the skirt andthe other member.
 14. The sealing device as claimed in claim 7, in whichthe snap-fit arrangement comprises a series of alternating resilientlydeformable ribs and grooves formed around each of the mutually facingsurfaces of the skirt and the other member the ribs of the skirt and theother member being deformable on assembly so as to engage with thecorresponding grooves of the member and the skirt.
 15. The sealingdevice as claimed in claim 7, in which the skirt is formed integrallywith the member by forming an endless slot in the material of the memberso that the slot is defined by mutually facing endless surfaces of theskirt and the member.
 16. The sealing device as claimed in claim 7, inwhich the skirt is manufactured from plastics material.
 17. The sealingdevice as claimed in claim 7, in which the skirt is configured to besufficiently resiliently deformable under a predetermined pressure rangeof fluid supplied into a gap between the mutually facing surfaces of theskirt and the member to which the skirt is attached, so as to deflecttowards the other member thus enhancing the sealing action of the atleast one rib between the skirt and the other member.